erate cost which will serve the purpose quite well. No set of observation instruments can be as satisfactory and useful without a barometer as with one, and if any serious attempts are to be made at prediction of weather changes such instrument is indispensable.

In weather study the use of the daily weather map is invaluable. It is a fact that such map displayed in the postoffice or other public place is almost or perfectly meaningless to ninety-nine out of a hundred observers, yet its explanation is very simple. Its language consists of but four symbols-the continuous heavy lines or isobars, the lines of dashes or isotherms, the arrows indicating the wind directions and the circles and dots placed. on these arrows, indicating clear, cloudy or rainy weather. The key to the weather conditions shown by any given map are the words "low" and "high" appearing in heavy faced type in two or three places on the map. The word "low" means low pressure, as shown by the barometer, which means that the region thus marked is overlain by light thin air. The region marked "high" is overlain by dense heavy air, which causes the mercury in the barometers to rise high. The isobars are commonly seen arranged around the "lows" and "highs" in concentric circles or ellipses. Each isobar indicates equal pressure or weight of air throughout its length, and from one isobar to the next the pressure varies one-tenth of an inch; that is, the difference in the weight of the air on two adjacent isobars on each square inch of the earth's surface is equal to a depth of one-tenth inch of mercury over the same area. The air becomes heavier as we go from "low" to "high" and vice versa.

This unequal weight of the air causes. it to move out from the high and in toward the low centers. The arrows indicate this air movement with great uniformity. It will be noticed that the arrows do not point directly toward the low nor directly from the high centers, but to the right of lines converging at the low center or radiating from the high center. The air moves from high pressure to low pressure regions under

the influence of gravity and it is deflected to the right of a direct line to or from these centers by the rotation of the earth. This results in a great whirlwind around each center, the air moving in a spiral, counter clockwise path toward the low center and in a spiral clockwise path from the high center. The movement of the air toward the low center is called a cyclone, that from the high center an anticyclone.

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Cyclones bring us our rainy and anticyclones our fair weather, and in the United States, particularly from September to May, these cyclones and anticyclones drift eastward across the country, bringing to any given point alternations of fair and foul weather once or twice a week. During the summer months the passage of these storms is much less marked, and the weather is much more uniform. In examining a weather map, it will be noticed that the isotherms, i. e., the lines of equal temperature, bend to the north on the east side of the low center of a cyclone and to the south to the west of the center. By noticing the arrows indicating wind directions it will be seen that in the east part of the cyclone, where the isotherms bend to the north, that the winds are south or southeast, while on the west of the center the winds are from the north or northwest. These different winds greatly affect the temperature, particularly in winter when the south winds bring warm air from the southern part of the country, and even from the Gulf of Mexico and Atlantic Ocean. The northwest winds bring cold air from the center of the continent, so that within a few hours we may experience a transition from tropical to frigid temperatures. It may be seen also that the south, southeast and east winds bring most of our rain storms, and that fair weather generally follows soon after the wind changes to the west or northwest. South and southeast winds bring rain. because moist, warm air is drawn from the Gulf of Mexico and from the Atlantic Ocean, which is cooled by being carried northward to cooler latitudes. About the low center the air that is drawn in from all sides rises and is cooled further

by expansion as it rises into less dense air, and also by mixture of the southerly warm air currents with the cold northerly currents. This cooling condenses the water vapor diffused through the air, and clouds and rain occur. The air in an anticyclone settles down from the upper atmosphere, being compressed and warmed in its downward movement, thus increasing its capacity for vapor and causing the small amount of visible moisture in the air to evaporate and disappear. Cold northwest winds moving to more southerly latitudes are warmed, clouds and mists are evaporated, and the phenomenon of “clearing off" occurs.

All the facts suggested for observation connect well with the study of the weather map. It is popular weather wisdom that southeast and south winds bring or presage rain, while northwest winds indicate the approach of fair weather. In studying the weather map it may be observed that cyclones with many isobars encircling the low center and lying close together are accompanied by strong winds, and large cyclones covering a large portion of the country are. commonly indicative of a general rain. The downpour of March 25th last accompanied a cyclone which occupied the central plain from the Appalachian to the Rocky mountains, and from Canada to the Gulf of Mexico. Summer rains are generally local thunder-storms, caused by the rising of columns of warm, moist air, which cools as it rises, causing the condensation of the vapor, the formation of the tall fleecy cumulus clouds and showers of rain. The summer weather maps show a very different arrangement of isobars and isotherms from those on the winter maps. The lines run irregularly across the map, and often no signs of cyclones or anticyclones can be seen for several days or even weeks in succession.

The observation of the weather lavs the basis for the determination of climate. The observer who keeps a record for a few years will find that the temper

ature ranges from ten to fifteen degrees below zero to one hundred to one hundred five above. Sometimes the mercury will fall for a single morning to twenty or twenty-five degrees below zero, which is an infrequent occurrence. A frequent range is from zero to one hundred above, and the average for the year is about midway between these points, or fifty degrees, for Indiana. This average is called the mean annual temperature. Averages based on ten-year periods will scarcely vary one degree in a half century. Rainfall measured from year to year shows for this region an average of forty inches per year. In 1901 but thirty-one inches fell, seven of which fell in June. From July 4th during forty-two days no rain occurred in many parts of Indiana. This was an abnormal year not matched by any in the lifetime of the proverbial "oldest inhabitant." In March of the present year more than one-fourth of our annual average fell, and one-eighth of it fell within one day. This rain, considering its wide extent, was the greatest that has occurred within the history of the State. This has, however, been surpassed in local thunder-storms, in one of which in 1895 seven inches of rain fell in Crawfordsville and vicinity within a a few hours.

Wind direction records show west winds on an average four days out of six. This shows the prevalence of the antitrade or westerly winds over this region, notwithstanding the variations due to the passage of cyclones.

A survey of the trees of any forest or orchard in one's neighborhood will show the effect of the antitrades on the position of the trunk and attitude of the branches of a greater number of trees.

Many facts of scientific interest and of practical value appear in the records and experience of the patient and faithful observer, and the training of the observational and reasoning powers is realized as fully as in any of the other lines of nature study.